The invention relates to a method of optical data processing, with a modulable source of light illuminating an optical assembly, and to a device for carrying out the method.
In such methods and devices, it is required, in particular, to optically perform various transformations, such as a folding, a correlation, a Fourier Transformation, etc.
A data processing method and device of this kind is described, for example, in the article "Electrooptical Signal Processing Module", by K. Bromey et al, SPIE Vol. 180 Real-Time Signal Processing II (1979). Provided is a two-dimensional photodetector arrangement which is illuminated through a mask by a module source of light, such as an LED. The mask is provided for each photocell of the photodector arrangement with a window of variable size. The size and distribution of these windows depends on the desired transformation. The image f.sub.n to be transformed with this method is serially scanned, whereby the intensity of the light radiated by the incoherent light source is modulated. Now, with this light, all the photocells of the photodetector arrangement, comprising charge-coupled storages (CCD) are simultaneously irradiated through the mask, with the photocharge produced per photocell in the CCD photodetector arrangement being a function of the light intensity and of the size of the windows of the mask.
As the light beam passes from one pixel of image f.sub.n to the next one, the total photodetector hitherto produced in the CCD photodetector arrangement is shifted by one storage location. With the image f.sub.n completely scanned, the photodetector arrangement contains a photocharge image corresponding to the transformation of image f.sub.n through the mask. This method may be applied to the transformation of both one- and two- dimensional data arrays f.sub.n. Two-dimensional data arrays require a two-dimensional mask, as well as a two-dimensional photodetector arrangement. One-dimensional data strings f.sub.n require a one-dimensional mask and a one-dimensional, i.e. linear, photodetector arrangement.
This method and device are disadvantageous in that the mask must be positioned very accurately relative to the photodetector arrangement, and that the maximum positioning accuracy can be obtained only with the mask fixedly and directly applied to the photodetector arrangement. This deprives the device of its versatility, since a separate assembly is needed for every transformation, such as a Fourier transformation, or a correlation.